A dense mattress, it is thick enough. It certainly works fine as a sofa mattress. Sleeping on it isn’t too bad. However, even with the foam core, its not built to sleep on for more than a few days at a time. I wouuld recommend this mattress as a primary futon mattress and a backup bed. You can’t go wrong. Only reason I didn’t give it 5 stars was because it has very little “give”.